Homeostasis, Gradients, Cell to Cell Communication, Cell Membrane, and Enzymes

What is flow?

the movement of substances (fluids, gases, and ions) within the body to maintain balance and support vital functions

what is flow driven by?

driven or influenced by concentration gradients, pressure differences, electrical potentials, and resistance

Bulk Flow

movement of a solution driven by a pressure gradient

Concentration

Amount of solute in a volume of solution

Diffusion

Movement of solutes through a solution

Electrical potential

Difference in charge between two points

Energy

Measure of a systems ability to do work

What is resistance?

-a force that opposes flow

-the opposition to the flow of substances like fluids or gases within the body

What factors can cause resistance in the body?

narrowed blood vessels (diameter)

viscosity of fluids

length of the pathway

temperature

number of open channels

a blockage

Hydrostatic Pressure

pressure in a fluid created by a vertical column or a pump

Osmosis

movement of water down a concentration gradient

Gradient

Difference in the magnitude of the concentration, electrical potential, pressure, or temperature between two point in a system

Homeostasis

-maintenance of physiology to be compatible with life

-stable internal environment

-maintenance of steady state

What is homeostasis regulated by?

feedback loops

What is true of equilibrium and homeostasis?

the human body at equilibrium is bad

-you do not want equal amounts of everything

-equilibrium = death

-instead we want to remain at steady state

What is steady state?

the maintenance of differences

-inside and outside of the cell

-pressure gradients

Involves a dynamic balance

-inputs and outputs are are continuously adjusted to maintain stability

Does steady state require energy?

Yes

How is steady state maintained?

Feedback loops

Does equilibrium require energy?

No, there is no net change so no energy is required

Variable

something under physiologic control that can change

-can be affected by internal or external factors

Set Point

the target value/range of a variable

Receptor

something that senses a signal

-monitors a physiological variable

Control Center

receives information from receptors

-determines if an action is warranted

Effector

something that responds to information from a control center

Positive Feedback Loop

Effector activity is in the same direction as the stimulus and it continuously amplifies the change

Negative Feedback Loop

counteract the change (stimulus)

-effector stops responding once steady state is regained

Concentration Gradient

when substances flow from areas of high concentration to low concentration

Osmotic Gradient

movement of substances across a membrane from low concentration to a high concentration, creating a balance

Pressure Gradient

fluids in the body flowing from regions of high pressure to low pressure

Electrical Gradient

Varying electrical charged in membranes that causes ions like sodium or potassium to move across cell boundaries

Temperature Gradient

guide the movement of heat energy

-cells and tissues generate heat through metabolic processes, creating hot spots. This heat then flows from areas of high temps to low temps, maintains a stable internal temp

What happens when there are two opposing gradients

the flow will depend on the net effect of both gradients, usually towards the stronger gradient

If there are two gradients acting in the same direction, what happens

they will enhance the flow

Cell to Cell Communication

cells talking to one another through signals sent from the nervous system or endocrine systems to allow for coordination of activities

-maintains balance and response to changes within the body

Transduction

process of converting one form of energy into another

-involved converting an external signal into an internal cellular response

chemical messenger

a molecule produced and released by a particular cell that carries information to target cells

-binding to a receptor causes a change in the function of that cell

-does not act independently

enzyme

Protein that acts as a biological Catalyst

-highly specific and binds with a specific substrate

-are necessary for chemical reactions to occur

Receptor

a protein molecule to which particular messenger molecules can bind

-when something binds, signal transduction and amplification occurs

-chang ein cell function causes a biological response to occur

Target Cell

a cell that has receptors for a particular chemical messenger molecule

-cell will change its function when the message is received

How does the nervous system use C2C communication?

neurons communicate through electrical impulses and chemical signals (neurotransmitters)

How does the endocrine system use C2C communication?

Uses hormones as messengers

How does the immune system use C2C communication?

immune cells use chemical signals to communicate

Sensory Systems in cell to cell communication

in systems like hearing, cells in the ear convert sound waves into electrical signals that are then transmitted to the brain

Why is is called the fluid mosaic model?

-molecules in the membrane are constantly moving which prevents the membrane from being completely impermeable

-molecules are arranged in a pattern

what factors contribute to fluidity?

Temperature

Cholesterol

Fatty Acids

how does temperature contribute to fluidity

heat causes molecules to spread out and become more permeable

how does cholesterol contribute to fluidity?

keeps molecules from binding too closely

how does fatty acids contribute to fluidity?

-saturated acids bind tightly causing decreased permeability

-unsaturated acids bind loosely causing increased permeability

Phosphate head

polar, hydrophilic

Fatty acid tail

nonpolar, hydrophobic

can fat or water soluble molecules travel directly through the membrane

fat soluble molecules, not water soluble

integral membrane proteins

embedded within the membrane

-assist with molecule movement

peripheral membrane proteins

found on the inner/outer surface

-assist with support, communication, enzymes

what are the four types of membrane proteins

Transporter

Receptor

Enzyme

Anchor

Transporter Protein

Allows for movement of specific molecules

Receptor Protein

Senses specific reactions

Enzymes

Speeds up chemical reactions

Anchor

links the intracellular and extracellular structures

Polar molecules

-Electrons are shared unequally

-molecule will have slightly different charges in different areas

Nonpolar molecules

Electrons are shared equally and molecule has the same charge throughout

What is true of small nonpolar molecules moving through the membrane

they are able to move through without help (no charge)

What is true of small polar molecules moving through the membrane

able to move through without help but at a slower rate due to slight charge

What is true of large nonpolar molecules moving through the membrane

able to pass through with no help but there size slows them down

What is true of large polar molecules moving through the membrane

they need help moving through the membrane since the charge prevents movement through the nonpolar section

-requires a channel

What is true of ions moving through the membrane

need help to move through

-charge prevents them from moving through the nonpolar section of the membrane

What do ions require to get through the membrane?

A channel

Where do substrates act?

binding occurs at the active site of an enzyme

why are enzymes specific?

they bind only with a specific substrate

Enzyme saturation

occurs when all active sites are filled with substrate

-causes the enzyme to work at its maximum rate

If you have enzyme saturation, what happens when you add more substrates on board?

Nothing, more substrates will not increase enzyme activity since they have no where to bind

Enzyme inhbition

When an active site is filled by a competitor that inhibits enzyme activity

What are the two types of enzyme inhibition

Competitive and Non competitive

Competitive Inhibition

inhibitor binds to the active site

Non Competitive Inhibition

inhibitor binds to a different spot on the enzyme and changes the shape of the enzyme

-the substrate cannot bind to the active site

What is the rate of energy production of enzymes determined by?

-Availability of substrate

-Amount of products

-Enzyme Activity

How do we want energy to be released in the body?

At a controlled rate since it is more efficient

Cofactor

A nonprotein molecule or ion that is required for the proper functioning of an enzyme (2nd key)

-enzyme will not work without it

Activation Energy

How much energy is required to run a specific reaction or break down bonds in a specific reactant

Temperature and Enzymes

when you raise core body temperature a little bit, enzyme activity will increase

when you raise core body temperature too much, the enzymes can denature and lower activity

denature

makes enzyme inactive, changes shape and function

pH and enzymes

changes in pH affect bonding properties between enzymes and reactants

-any alteration of pH decreases enzyme activity

Substrate

something that an enzyme acts on and is then converted into something else

If you have more substrate, what do you have

more enzyme activity

Products of Enzymes

something produced with a substrate

if there is an excess of enzyme product, what happens

there is no need to produce more product so enzyme activity is reduced

Affinity

an attraction between substances

If there is a higher affinity between an enzyme and substrate, what happens

there will be increased enzyme activity and vice versa